Running control device for a vehicle

ABSTRACT

A cruise control system for an automotive vehicle controls a speed of own vehicle estimating conditions not only when the own vehicle passes through the intersection but also when the preceding vehicle passes through the intersection, for permitting travel on the ordinary road with a given distance. The cruise control system includes traffic signal characteristics obtaining means for obtaining characteristics of a traffic signal ahead, road information obtaining means for obtaining intersection information including a distance to an intersection, intersection arrival time calculating means for calculating arrival timing of the own vehicle and the preceding vehicle on the basis of a distance to the intersection, an own vehicle speed and a preceding vehicle traveling condition, traffic signal condition estimating means for estimating the condition of the traffic signal on the basis of the traffic signal characteristics and the intersection arriving time and control content modifying means for modifying a content of cruise control of the own vehicle depending upon the estimated traffic signal condition.

BACKGROUND OF THE INVENTION

[0001] The present invention relates generally to a running controldevice for a vehicle. More particularly, the invention relates to acruise control system for an automotive vehicle which can perceive acondition of coming traffic signal installed on a road, on which the ownvehicle travels, and appropriately control a speed of the own vehicleand a distance to a preceding vehicle.

[0002] According to advancement of performance of automotive vehicle, ithas been more important to provide preventive security by recognizingenvironmental condition, in which own vehicle travels for detecting acondition where accident tends to occur, to given an alarm to a driverfor encouraging taking operation for avoiding danger and preventingaccident before occurring by automatically controlling the vehicle inpositive manner.

[0003] More particularly, an automatic cruise control systems whichmeasures a distance to a preceding vehicle traveling ahead of ownvehicle using a laser radar or a millimeter wave radar for cruising withcontrolling the distance constant, have been commercialized. While suchsystems are premised on use on the highway, application of such systemfor traveling on ordinary roads toward the future.

[0004] Therefore, as prior arts, systems disclosed in Japanese PatentApplication Laid-Open No. 3-201100(1991), Japanese Patent ApplicationLaid-Open No. 3-260899(1991)and Japanese Patent Application Laid-OpenNo. 11-250399(1999). The conventional system disclosed in JapanesePatent Application Laid-Open No. 3-20110 recognizes condition of atraffic signal by image processing to announce a condition of thetraffic signal to the driver when the own vehicle reaches a position ofa predetermined distance to the traffic signal, and causes decelerationof the vehicle at red light. On the other hand, the conventional systemdisclosed in Japanese Patent Application Laid-Open No. 3-260899 hasmeans for detecting color information of the traffic signal to stopoperation of distance control when a color of the detected trafficsignal is a predetermined color.

[0005] On the other hand, the conventional system disclosed in JapanesePatent Application Laid-Open No. 11-250399 receives a distance to anintersection and a condition of the traffic signal from a on-roadequipment distanced from the intersection for a predetermined distance,and performs control.

[0006] On the other hand, in the conventional system, a condition of thetraffic signal is estimated the condition of the traffic signal when theown vehicle passes through the intersection on the basis of the receiveddistance to the intersection and a speed of the own vehicle and makesjudgment whether the own vehicle can stop at the intersection at apredetermined deceleration characteristics. Then, when the own vehiclecan stop at the intersection at the predetermined decelerationcharacteristics but cannot pass through the intersection safely, analarm is given to the driver. On the other hand, when the own vehiclecannot stop at the intersection at the predetermined decelerationcharacteristics, an alarm is given to the driver even when the ownvehicle can pass the intersection safely.

[0007] However, in the conventional automatic cruise control system,upon traveling on the ordinary road, various drawbacks are encountered.Namely, since the automatic cruising system measures only distance, ifthe preceding vehicle passes through the intersection at yellow light orred light, the own vehicle can follow the preceding vehicle despite ofthe fact that the traffic signal is red light.

[0008] On the other hand, since deceleration is taken place only inconsideration of the condition of the traffic signal when the ownvehicle passes through the intersection, unnecessary deceleration can becaused, and deceleration with taking stoppage of the preceding vehicleinto account cannot be performed. Therefore, more delicate vehicledistance control cannot be performed.

SUMMARY OF THE INVENTION

[0009] The present invention has been worked out in view of the problemsset forth above. Therefore, it is an object of the present invention toprovide a cruise control system for an automotive vehicle to controlspeed of own vehicle estimating conditions not only when the own vehiclepasses through the intersection but also when the preceding vehiclepasses through the intersection, for permitting travel on the ordinaryroad with a given distance.

[0010] In order to accomplish the above-mentioned object, a cruisecontrol system for an automotive vehicle, according to one aspect of thepresent invention, for controlling cruising of own vehicle withmaintaining a distance to a preceding vehicle constant, comprises:

[0011] traffic signal characteristics obtaining means for obtainingcharacteristics of a traffic signal ahead;

[0012] road information obtaining means for obtaining intersectioninformation including a distance to an intersection;

[0013] intersection arrival time calculating means for calculatingarrival timing of the own vehicle and the preceding vehicle on the basisof a distance to the intersection, an own vehicle speed and a precedingvehicle traveling condition;

[0014] traffic signal condition estimating means for estimating thecondition of the traffic signal on the basis of the traffic signalcharacteristics and the intersection arriving time; and

[0015] control content modifying means for modifying a content of cruisecontrol of the own vehicle depending upon the estimated traffic signalcondition.

[0016] On the other hand, in the cruise control system for an automotivevehicle may further comprise right and left turn control signalgenerating means for generating operation pattern of the own vehiclefrom a state of turn signal or a route information to a destinationgenerated by the road information obtaining means to input to thecontrol content modifying means.

[0017] The traffic signal characteristics obtaining means may includetraffic signal characteristics measuring means for measuringcharacteristics of the traffic signal and traffic signal characteristicslearning means for learning a traffic signal characteristics measured bythe traffic signal characteristics measuring means.

[0018] The traffic signal characteristics learning means may learnintersection information from the road information obtaining means withcorrespondence to the intersection information.

[0019] According to another aspect of the present invention, a cruisecontrol system for an automotive vehicle, for controlling cruising ofown vehicle with maintaining a distance to a preceding vehicle constant,comprises:

[0020] traffic signal characteristics obtaining means including imagepick-up means having zooming means, image processing means obtaining atraffic signal characteristics by processing an image of the imagepick-up means and communication means, for serving as measuring meansfor obtaining characteristics of a traffic signal ahead;

[0021] road information obtaining means for obtaining intersectioninformation including a distance to an intersection ahead;

[0022] intersection arrival time calculating means for calculatingarrival timing of the own vehicle and the preceding vehicle on the basisof a distance to the intersection, an own vehicle speed and a precedingvehicle traveling condition;

[0023] traffic signal condition estimating means for estimating thecondition of the traffic signal on the basis of the traffic signalcharacteristics and the intersection arriving time;

[0024] right and left turn control signal generating means forgenerating operation pattern of the own vehicle from a state of turnsignal or a route information to a destination generated by the roadinformation obtaining means to input to the control content modifyingmeans;

[0025] control content modifying means for modifying a content of cruisecontrol of the own vehicle depending upon the estimated traffic signalcondition; and

[0026] alarm means for generating a corresponding alarm beforehand ofmodifying the content of control.

[0027] On the other hand, the cruise control system for the automotivevehicle has communication means for obtaining the traveling condition ofthe preceding vehicle from outside. On the basis of the travelingcondition (distance and relative speed) of the preceding vehicleobtained via the communication means, the intersection arriving time ofthe preceding vehicle and the signal condition (red, green or yellow) atarrival timing are estimated to perform vehicle control. Here, thetraveling condition of the preceding vehicle from the communicationmeans may be the traveling condition of one or more preceding vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be understood more fully from thedetailed description given hereinafter and from the accompanyingdrawings of the preferred embodiment of the present invention, which,however, should not be taken to be limitative to the invention, but arefor explanation and understanding only.

[0029] In the drawings:

[0030]FIG. 1 is a block diagram showing a functional construction of oneembodiment of a cruise control system for an automotive vehicleaccording to the present invention;

[0031]FIG. 2 is an explanatory illustration for the case of obtaining atraffic signal characteristics;

[0032]FIG. 3 is a block diagram showing a construction of roadinformation obtaining means;

[0033]FIG. 4 is an explanatory illustration of a traffic signalcondition estimating method;

[0034]FIG. 5 is a block diagram showing a construction of the cruisecontrol system for the automotive vehicle;

[0035]FIG. 6 is a flowchart for discussing a process of target distancesetting means and speed command setting means;

[0036]FIG. 7 is a flowchart for discussing a process of vehicle speedcontrol means;

[0037]FIG. 8 is an illustration for discussing a control contentmodifying method;

[0038]FIG. 9 is an illustration for discussing an example of a speedcommand Vcop generating method;

[0039]FIG. 10 is an illustration for discussing another example of aspeed command Vcop generating method;

[0040]FIG. 11 is a block diagram for discussing a constriction oftraffic signal characteristics obtaining means;

[0041]FIG. 12 is a block diagram for discussing a constriction oftraffic signal characteristics obtaining means;

[0042]FIG. 13 is a block diagram for discussing another constriction oftraffic signal characteristics obtaining means;

[0043]FIG. 14 is a block diagram showing another construction of thecruise control system for the automotive vehicle according to thepresent invention;

[0044]FIG. 15 is a block diagram showing a construction of precedingvehicle information obtaining means;

[0045]FIG. 16 is a block diagram showing a further construction of thecruise control system for the automotive vehicle according to thepresent invention; and

[0046]FIG. 17 is an explanatory illustration of a control mode ofcontrol content modifying means.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0047] The present invention will be discussed hereinafter in detail interms of the preferred embodiment of the present invention withreference to the accompanying drawings. In the following description,numerous specific details are set forth in order to provide a thoroughunderstanding of the present invention. It will be obvious, however, tothose skilled in the art that the present invention may be practicedwithout these specific details. In other instance, well-known structureare not shown in detail in order to avoid unnecessary obscurity of thepresent invention.

[0048]FIG. 1 shows a block diagram of one embodiment of a cruise controlsystem for an automotive vehicle. The shown embodiment of the cruisecontrol system for the automotive vehicle is constructed with trafficsignal characteristics obtaining means 1, road information obtainingmeans 2, intersection arriving time calculating means 3, traffic signalcondition estimating means 4, control content modifying means 5, cruisecontrol means 6 and alarm means 7, in general.

[0049] The traffic signal characteristics obtaining means 1 isconstructed with image pick-up means (101) for picking up an image of atraveling direction of an own vehicle, and image processing means (102,see FIG. 12) for processing the image picked up by the image pick-upmeans (101), for example. By executing processing procedure which willbe discussed later, characteristics Cs of the traffic signal (red lightperiod Tr, green light period Tb, yellow light period Ty and an elapsedtime T from beginning of a signal condition cycle to a current time)shown in FIG. 2 is obtained to output to the traffic signal conditionpredicting means 4.

[0050] Here, the characteristics Cs of the traffic signal obtained bytraffic signal characteristics obtaining means 1 is the red light periodTr, the green light period Tb, the yellow light period Ty and theelapsed time T from beginning of the cycle to the current time as takinggreen, yellow and red light periods as one cycle. The traffic signalcharacteristics obtaining means can be realized by the image pick-updevice, such as a TV camera, and an image processing device, forexample, can recognize the traffic signal by processing the image pickedup by the image processing device and can measure the green lightperiod, the yellow light period and the read light period withcorrespondence to the current time. In the alternative, the red lightperiod, the green light period and the yellow light period can beobtained from the traffic signal provided on the road, the control unitor other on-road equipment through communication means.

[0051] On the other hand, the road information obtaining means 2 can berealized by employing a navigation device as means for calculating adistance L to an intersection, to which an own vehicle is approaching,using an own position obtained by GPS or the like and a road map. Theroad information obtaining means 2 can be constructed with thenavigation device 20 utilizing GPS as shown in FIG. 3 and a GPS antenna21, for example. Namely, a traveling position of the own vehicle isderived utilizing the GPS to discriminate a road on which the ownvehicle is traveling and an intersection, to which the own vehicle isapproaching by establishing correspondence between the derived travelingposition and the road map stored in the navigation device 20, tocalculate a distance L to the intersection, to which the own vehicle isapproaching is calculated from information, such as shape of the road orso forth stored in the road map. Since the discriminated road and theintersection are stored in the road map with assigning unique numbers,the road number and the intersection number can be output together withthe discriminated road and the intersection.

[0052] When a route calculating function is provided in the navigationdevice, an optimal route from a starting point to a destination can becalculated, Therefore, on the basis of the route calculated, informationto go straight, to turn right or to turn left can also be output.

[0053] The intersection arriving time calculating means 3 estimatestimings to arrive the intersection of the own vehicle and the precedingvehicle, using the distance to the intersection, an own vehicle speedand traveling condition of the preceding vehicle (distance and relativespeed). Now, assuming that a distance to the intersection output fromthe road information obtaining means 2 is L, an own vehicle speed outputby the cruise control means 6 is V0, the distance to the precedingvehicle is Dm and a relative speed with the preceding vehicle is Vr, atiming Ts and Tp of arrival to the intersection of the own vehicle andthe preceding vehicle are estimated by the following equation to outputto the traffic signal condition estimating means 4.

Ts=L/Vo

Tp=(L−Dm)/Vs

Vs=Vo+Vr

[0054] On the other hand, traffic signal condition estimating means 4estimates the signal condition (green light, yellow light or red light)upon arrival to the intersection of the own vehicle and the precedingvehicle on the basis of timing of arrival to the intersection of the ownvehicle and the preceding vehicle and the traffic signal characteristics(red light period Tr, green light period Tb, yellow light period Ty andan elapsed time T from beginning of a signal condition cycle to acurrent time). Then, the traffic signal condition estimating means 4estimates conditions STs and STp of the traffic signal upon arrival ofthe own vehicle and the preceding vehicle as shown in FIG. 4 using thecharacteristics Cs of the traffic signal output by the traffic signalcharacteristics obtaining means 1 and intersection arriving timing Tsand Tp of the own vehicle and the preceding vehicle output by theintersection arriving time calculating means 3. In an example of FIG. 4,there is shown that when the preceding vehicle arrives the intersection,the traffic signal is a red light condition Tr, and when the own vehiclearrives the intersection, the traffic signal is a blue light conditionTb.

[0055] The control content modifying means 5 controls traveling ofvehicle by making judgment whether a distance control is to be continuedor to perform decelerating operation depending upon a decelerationcharacteristics according to a distance to the intersection and the ownvehicle speed depending upon the estimated condition of traffic signal(green light, yellow light or red light) upon arrival to theintersection of the own vehicle and the preceding vehicle. On the otherhand, it is also possible to modify the decelerating operation dependingupon the signal condition (green light, yellow light or red light) uponarrival to the intersection of the own vehicle and the precedingvehicle. A traveling control mode M and a speed command Vcop are outputon the basis of the estimated traffic signal conditions STs and STpoutput by the traffic signal condition estimating means 4, a distance tothe intersection L output by the road information obtaining means 3 andthe own vehicle speed VO output by the cruise control means 6.Furthermore, when a traveling control mode is varied, a control signalSa for generating an alarm notifying the variation of the travelingcontrol mode to output to the alarm means 7.

[0056] The alarm means 7 provides an alarm to the driver by sound,light, vibration or the like before modification of the control contentin practice.

[0057] The cruise control means 6 is a control device for driving theown vehicle to travel with maintaining the distance to the precedingvehicle constant, and is constructed as shown in FIG. 5, for example.The cruise control means 6 includes a radar 605 having a target distance(Dr) setting means 607, a relative speed (Vr) detecting means 602, adistance (Dm) detecting means 604, a speed command (Vcmd) setting means608, a vehicle speed control means 609, an own vehicle speed detectingmeans 610, a throttle actuator 611, a transmission actuator 612 and abrake actuator 613.

[0058] As the own vehicle speed detecting means 610 detecting the ownvehicle speed Vo, a wheel speed sensor detecting a vehicle speed from arotation speed of the wheel may be employed, for example. The radar isconstructed with a millimeter wave radar for example and has own vehiclespeed detecting means and relative speed detecting means 602 formeasuring and outputting respective of the distance Dm and the relativespeed Vr.

[0059] The target distance setting means 607 sets a target distance Dron the basis of the own vehicle speed Vo detected by the own vehiclespeed detecting means 610.

[0060] In the speed command setting means 608, a speed command Vcmd isset on the basis of the target distance Dr, the measured distance Dm andthe measured relative speed Vr.

[0061] The vehicle speed control means 609 derives a throttle valve opendegree command, a shift command and a brake command on the basis of theown vehicle speed Vo, the speed command Vcmd, the distance Dm, therelative speed Vr, the control mode M and the speed command Vcop tocontrol the throttle actuator 611, the transmission actuator 612 and thebrake actuator 613.

[0062] Here, the control content modifying means 5, the target distancesetting means 607, the speed command setting means 608 and the vehiclespeed control means 609 may be realized by executing respectivelycorresponding control programs by a computer, for example. A processcorresponding to respective control programs will be discussedhereinafter in detail.

[0063] At first, the process to be executed by the target distancesetting portion 607 and the speed command setting means 608 will bediscussed with reference to the flowchart of FIG. 6.

[0064] At step 301, the own vehicle speed Vo is taken out from the ownvehicle detecting means 610. At step 602, the target distance Dr is setdepending upon the own vehicle speed Vo. As these setting method, forexample, when the own vehicle speed Vo is lower than 18 km/h, the targetdistance Dr is set at 10 m. When the own vehicle speed Vo is in a rangebetween 18 km/h to 45 km/h, the target distance is increased from 10 min proportion to increasing of the vehicle speed. When the own vehiclespeed Vo is 45 km/h, the target distance Dr is set at 25 m. Even whenthe vehicle speed is higher than or equal to 45 km/h, the targetdistance is increased in proportion to increasing of the own vehiclespeed. When the own vehicle speed is 90 km/h, the target speed is set at75 m. As an alternate setting method, a method for deriving the targetdistance by multiplying the own vehicle speed Vo by a predeterminedperiod (for example, 1 second).

[0065] At step 303, the distance Dm measured by the distance detectingmeans 605 is taken out. Furthermore, at step 304, the measured relativespeed Vr is taken out. At step 305, the speed command Vcmd is derivedfrom the target distance Dr, the distance Dm, the relative speed Vr andthe own vehicle speed Vo by the following equation 1:

V _(cmd) =Vo+Ki∫ ₀ ^(t)(Dr−Dm)dt+Kp(Dr−Dm)+Kd•Vr

[0066] wherein ki is a coefficient for modifying the target speeddepending upon a difference between the target distance Dr and themeasured distance Dm when the difference is maintained for apredetermined period, t is the predetermined period, Kp is a coefficientfor modifying the target speed depending upon the difference between thetarget distance Dr and the measured distance Dm, Kd is a coefficient formodifying the target speed depending upon the relative speed. Thesevalues are determined by OFF line by simulation, experiments and soforth and are incorporated in a vehicle travel control program asparameters.

[0067] Concerning the process to be executed by the vehicle speedcontrol means 609, discussion will be given with reference to theflowchart in FIG. 7. At step 401, the control mode M is taken out fromthe control content modifying means 5. At step 402, judgment is madewhether the control mode M is designating use of the speed command Vcopgenerated by the control content modifying means 5. If use of the speedcommand Vcop is not designated, the process is advanced to step 404, andif use of the speed command Vcop is designated, the process is advancedto step 403.

[0068] At step 403, when the use of the speed command Vcop isdesignated, the speed command Vcop is taken out from the control contentmodifying means 5 and set the same as the speed command Vcmd.

[0069] At step 404, a speed control target torque Tcmd is derived by thefollowing equation 2.

T _(cmd) =Kj∫ ₀ ^(t)(Vcmd−Vo)dt+Kq•Vo

[0070] wherein Kj and Kq are predetermined control constants, in whichKj is a coefficient for modifying a target torque depending upon timeintegral (distance to move for the predetermined period at a speed ofthe difference) of the difference between the target speed and the ownvehicle speed, and Kq is a coefficient for modifying the target torquedepending upon the own vehicle speed.

[0071] At step 405, the speed control target torque Tcmd is comparedwith a predetermined target torque threshold value Tth. The targettorque threshold value Tth is a threshold value for selecting whetherthe own vehicle speed Vo is to be controlled mainly using the throttleopen degree command or the own vehicle speed Vo is to be controlledmainly using the brake command. When Tcmd≧Tth, a process from step 406to step 408 is executed and when Tcmd<Tth, a process from step 409 tostep 411 is executed.

[0072] When Tcmd≧Tth, acceleration control mainly using the throttleopen degree command and deceleration control mainly using engine brakingare performed. At step 406, the throttle open degree command is set. Thethrottle open degree command is set from a target engine torque and anengine revolution speed by calculating the target engine torque from acurrent transmission speed ratio and the speed control target torqueTcmd. This utilizes a relationship between the engine revolution speed,the throttle valve open degree and the engine torque.

[0073] Next, at step 407, a shifting command is set. When the speedcommand target torque Tcmd requires deceleration by engine braking, theshifting command is set for performing down-shifting. Then, at step 408,a brake command is set. Here, since it is not required to operate thebrake, the brake command is set for releasing the brake.

[0074] On the other hand, when Tcmd<Tth, deceleration control isperformed mainly using the brake. At step 409, since deceleration isperformed by controlling the brake, the throttle open degree is set tofully close. At step 410, a transmission speed ratio of the transmissionactuator 612 is set. At step 411, the brake command is set dependingupon the speed command target torque Tcmd. Then, on the basis of thethrottle open degree command, the throttle actuator 611 is driven. Thetransmission actuator 612 is driven on the basis of the shift command.The brake actuator 613 is driven on the basis of the brake command.Thus, own vehicle speed is controlled.

[0075] Next, the process to be executed by the control content modifyingmeans will be discussed with reference to FIG. 8.

[0076] In FIG. 8, (A) shows the condition of the traffic signal uponarrival to the intersection of the own vehicle and the preceding vehicleby ▴ and Δ which can be classified into twelve states depending upon thetraffic signal condition of the preceding vehicle, namely (1) to (12).Operation of the control content modifying means 5 in each state will bediscussed hereinafter.

[0077] In (A) of FIG. 8, the states (1) to (3) show the condition whereno preceding vehicle is present and represents the state where the ownvehicle travels at low speed. In this condition, since is only requiredto consider the condition of the traffic signal when the own vehiclereaches the intersection, the following operation is considered ascontrol mode M of the own vehicle. Hereinafter, the control modes Mgenerated depending upon control states (1) to (12) generated by thecontrol content modifying means 5 will be shown in (B) of FIG. 8.

[0078] State (1): Since the own vehicle enters into the intersection atgreen light, it is only required to maintain the distance control as is.Accordingly, the control mode commands to use the speed command Vcmd ofthe speed command setting means 608.

[0079] State (2): Since the own vehicle enters into the intersection atyellow light, it is required to stop at the intersection. Accordingly,the control mode M commands to use the speed command Vcop of the controlcontent modifying means 5. As a method for generating the speed command,it is required to set the own vehicle speed zero at the intersection,for example. Therefore, a pattern shown in FIG. 9 using the intersectiondistance L and the own vehicle speed Vo can be considered.

[0080] State (3): Since the own vehicle enters into the intersection atred light, it is required to stop at the intersection. Accordingly, thecontrol mode M commands to use the speed command Vcop of the controlcontent modifying means 5. For the speed command Vcop, the same patternas the state (2) can be used.

[0081] States (4) to (6) show the condition where the preceding vehicleenters into the intersection at green light. In these states, since thesimilar controls to those at states (1) to (3) are to be performed, thefollowing operations are considered as control modes M of the ownvehicle.

[0082] State (4): Since the own vehicle enters into the intersection atgreen light, it is only required to maintain the distance control as is.Accordingly, the control mode commands to use the speed command Vcmd ofthe speed command setting means 608.

[0083] State (5): Since the own vehicle enters into the intersection atyellow light, it is required to stop at the intersection. Accordingly,the control mode M commands to use the speed command Vcop of the controlcontent modifying means 5. As a method for generating the speed command,it is required to set the own vehicle speed zero at the intersection,for example. Therefore, a pattern shown in FIG. 9 using the intersectiondistance L and the own vehicle speed Vo can be considered.

[0084] State (6): Since the own vehicle enters into the intersection atred light, it is required to stop at the intersection. Accordingly, thecontrol mode M commands to use the speed command Vcop of the controlcontent modifying means 5. For the speed command Vcop, the same patternas the state (5) can be used.

[0085] The states (7) to (9) shows the states where the precedingvehicle enters into the intersection at the yellow light. At thiscondition, it can be considered a case where the preceding vehiclepasses through the intersection at the yellow light and a case where thepreceding vehicle stops at the yellow light. The control contentmodifying means 5 is required to consider the case where the precedingvehicle passes through the intersection, in view point of safety.However, upon generating the speed command Vcop, it may be generated inconsideration that the preceding vehicle stops at the intersection.Accordingly, as the control modes M of the own vehicle, the followingoperations are considered.

[0086] State (7): Since the own vehicle enters into the intersection atthe yellow light, it is required to stop at the intersection.Accordingly, the control mode M commands to use the speed command Vcopof the control content modifying means 5. As a generation method of thespeed command Vcop, similar consideration as the states (5) and (6) istaken, and in consideration that the preceding vehicle stops at theintersection, the own vehicle speed is set to be zero at a point L1derived by subtracting a value taking the vehicle length of thepreceding vehicle into account from the intersection distance L as shownin FIG. 10, for example. As the vehicle length of the preceding vehicle,the vehicle length of a full size vehicle is programmed as defaultlength, or in the alternative, when the traffic signal characteristicsobtaining means 1 is constructed with the image pick-up device and theimage processing device, the number plate of the preceding vehicle isrecognized to discriminate the kind of the preceding vehicle to use thevehicle length depending upon the kind of the preceding vehicle.

[0087] State (8): Since the own vehicle enters into the red light, it isrequired to stop at the intersection. Accordingly, the control mode Mcommands to use the speed command Vcop of the control content modifyingmeans 5. For the speed command Vcop, the same pattern as the state (7)can be used.

[0088] State (9): Since the own vehicle enters into the intersection atgreen light to pass, the distance control can be maintained as is. Ifthe preceding vehicle stops at the yellow signal, the distance controlwill work. Accordingly, the control mode M command to use the speedcommand Vcmd of the speed command setting means 608.

[0089] States (10) to (12) show the condition where the precedingvehicle enters into the intersection at red light. At this time, it canbe considered that the preceding vehicle stops at the intersection, theown vehicle may maintain the distance control. Accordingly, as all ofcontrol mode M of states (10) to (12), it is commanded to use the speedcommand Vcmd of the speed command setting means 608.

[0090] In FIG. 8, as taking that traffic signal conditions of the greenlight, the yellow light and the read light one cycle, consideration hasbeen given for the case where the traffic signal conditions of thepreceding vehicle and the own vehicle falls within one cycle. However,it is possible that the traffic signal conditions of the precedingvehicle and the own vehicle extend over two cycles. It should be notedthat, in this case, since it can be considered that a distance to thepreceding vehicle is sufficient, it may be possible to perform cruisecontrol or travel control with maintaining distance control until thetraffic signal conditions of the preceding vehicle and the own vehiclefalls within one cycle as shown in FIG. 8.

[0091] On the other hand, when the control content modifying means 5varies the travel control mode M, the control signal Sa (FIG. 1) isgenerated in order to generate an alarm for notifying this fact tooutput to the alarm means 7.

[0092] The traffic signal characteristics obtaining means 1 shown inFIG. 1 for obtaining the characteristics of the traffic signal (forexample, among one cycle of the green light, the yellow light and thered light, red light period Tr, green light period Tb, yellow lightperiod Ty and an elapsed time T from beginning of a signal conditioncycle to a current time) is constructed as shown in FIG. 11, forexample. The traffic signal characteristics obtaining means 1 has atraffic signal characteristics measuring means 10 and a learning means11. In the traffic signal characteristics measuring means 10, thecharacteristics of the traffic signal is measured. On the other hand, inthe learning means, the traffic signal characteristics measured by thetraffic signal characteristics measuring means 10 is stored togetherwith the intersection number or the road number. When the traffic signalcharacteristics measuring means 10 cannot measure the traffic signalcharacteristics, or measurement is difficult, the stored traffic signalcharacteristics preliminarily stored is read out by the learning means11 on the basis of the intersection number or the road number.

[0093] The traffic signal characteristics measuring means 10 isconsidered to be constructed as shown in FIG. 12. In FIG. 12, there isprovided the image pick-up means 10 for picking up image relating totravel of own vehicle and the image processing means 102 for processingthe image picked up by the image pick-up means 101. In the constructionof FIG. 12, as a method for measuring the traffic signalcharacteristics, color information of green, yellow and red is detectedfrom the image picked up by the image pick up means 101 to recognize thetraffic signal by making judgment whether the arrangement of green,yellow and red is the same as the traffic signal or not. Then, byperforming this process for sequence of images, each period of the greenlight, the yellow light and the red light are measured. The measuredtraffic signal characteristics is output to the traffic signal conditionestimating means 4, and in conjunction therewith to output to thelearning means 11. For example, when the image pick-up means 101 cannotpick up the image of the traffic signal for presence of the large sizevehicle in front of the own vehicle, the traffic signal characteristicsis read out from the learning means 11 to output the readoutinformation. On the other hand, when a distance to the intersection islong, the image of the traffic signal picked up is small. Therefore, byusing a lens having a zooming mechanism, a magnification of the zoomingmechanism depending upon the distance to the lens is derived to generatea zoom control signal Zm to control the zoom lens.

[0094] Another construction of the traffic signal characteristicsmeasuring means 10 is shown in FIG. 13. The construction of FIG. 13 isto obtain the characteristics of the traffic signal from the trafficsignal installed on the road or the control unit thereof through thecommunication means. The traffic signal characteristics measuring means10 can be realized by the communication means 103 using radio wave orlight. In the communication means, the measured traffic signalcharacteristics Cs is output to the traffic signal condition estimatingmeans 4 and also to the learning means 11.

[0095] The learning means 11 can be realized using a memory, forexample.

[0096] In the embodiment of the present invention shown in FIG. 1, atraveling condition (distance and relative speed) of the precedingvehicle is obtained from the cruise control means 6. However, it is alsopossible to have a construction shown in FIG. 14 as a further embodimentof the present invention. The embodiment shown in FIG. 14 is to obtainthe traveling condition of the preceding vehicle from the control unitinstalled on the road, and is provided with preceding vehicleinformation obtaining means 8 in addition to the embodiment of FIG. 1.The preceding vehicle information obtaining means 8 can be constructedwith communication means 81 and processing means 82 as shown in FIG. 15.The communication means 81 receives traveling condition of the precedingvehicle from the control unit on the road using the radio wave or light.The processing means 82 outputs the traveling condition of the receivedpreceding vehicle to the intersection arriving time measuring means 3.

[0097] When the embodiment shown in FIG. 14 is used, it becomes possibleto obtain traveling condition of a plurality of preceding vehiclestraveling around the own vehicle from the control unit on the road. Inthis case, since the intersection arriving time and the traffic signalcondition can be estimated for the vehicle traveling ahead of thepreceding vehicle which the own vehicle follows. Therefore, furtherprecise control can be realized to contribute for improvement of ridingcomfort.

[0098] Furthermore, as the embodiment for realizing the presentinvention, a construction shown in FIG. 16 is considered, for example.In the embodiment shown in FIG. 16, it is intended to control ownvehicle in consideration of the vehicles coming from the oppositedirection and foot passengers or the like when the own vehicle turnsright or left in the intersection. Therefore, in addition to theconstruction of the embodiment of FIG. 1, left and right turn controlsignal generating means 9 is provided. The left and right turn controlsignal generating means may also be provided in the embodiment shown inFIG. 14.

[0099] The left and right turn control signal generating means 9receives state of a turn signal and a route information (go straight, toturn right or to turn left) to the destination generated by the roadinformation obtaining means to generate right or left turn controlsignal R/L when at least one of the state of the turn signal and theroute information indicates right turn or left turn to output to thecontrol content modifying means. The right or left turn control signalR/L has a pattern that R/L=0 when own vehicle has to go straight throughthe intersection, R/L=1 when the own vehicle has to turn right in theintersection and R/L=2 when the own vehicle has to turn left in theintersection. The control content modifying means 5 modifies the contentof cruise control of the own vehicle on the basis of the value of theright or left control signal R/L. For example, the operating conditions(1) to (12) of the control content modifying means 5 depending uponsignal condition of the own vehicle and the preceding vehicle is onlyfor the case of R/L=0 (straight). When R/L=1 or 2, an alarm forannouncing necessity of checking the vehicles coming from the oppositedirection and foot passengers for the driver. Also, the speed commandgenerate the control mode M to use the speed command Vcop generated bythe control content modifying means 5. The control mode of the controlcontent modifying means 5 is shown in FIG. 17 corresponding to the rightand left turn control signal R/L.

[0100] With the present invention, upon traveling on the ordinary roadfollowing the preceding vehicle, entering into the intersection at theyellow light following the preceding vehicle can be avoided to permittraveling of the driver without causing fear of insecurity.

[0101] Although the present invention has been illustrated and describedwith respect to exemplary embodiment thereof, it should be understood bythose skilled in the art that the foregoing and various other changes,omission and additions may be made therein and thereto, withoutdeparting from the spirit and scope of the present invention. Therefore,the present invention should not be understood as limited to thespecific embodiment set out above but to include all possibleembodiments which can be embodied within a scope encompassed andequivalent thereof with respect to the feature set out in the appendedclaims.

What is claimed is:
 1. A cruise control system for an automotivevehicle, for controlling cruising of own vehicle with maintaining adistance to a preceding vehicle constant, comprising: traffic signalcharacteristics obtaining means for obtaining characteristics of atraffic signal ahead; road information obtaining means for obtainingintersection information including a distance to an intersection;intersection arrival time calculating means for calculating arrivaltiming of the own vehicle and the preceding vehicle on the basis of adistance to the intersection, an own vehicle speed and a precedingvehicle traveling condition; traffic signal condition estimating meansfor estimating said condition of the traffic signal on the basis of thetraffic signal characteristics and said intersection arriving time; andcontrol content modifying means for modifying a content of cruisecontrol of the own vehicle depending upon said estimated traffic signalcondition.
 2. A cruise control system for an automotive vehicle as setforth in claim 1 , wherein communication means is provided in saidtraffic signal characteristics obtaining means for obtaining saidtraffic signal condition or traveling condition of said precedingvehicle.
 3. A cruise control system for an automotive vehicle as setforth in claim 1 , which further comprise right and left turn controlsignal generating means for generating operation pattern of the ownvehicle from a state of turn signal or a route information to adestination generated by said road information obtaining means to inputto said control content modifying means.
 4. A cruise control system foran automotive vehicle as set forth in claim 1 , wherein said trafficsignal characteristics obtaining means includes traffic signalcharacteristics measuring means for measuring characteristics of thetraffic signal and traffic signal characteristics learning means forlearning a traffic signal characteristics measured by the traffic signalcharacteristics measuring means.
 5. A cruise control system for anautomotive vehicle as set forth in claim 4 , wherein said traffic signalcharacteristics learning means learns intersection information from saidroad information obtaining means with correspondence to the intersectioninformation.
 6. A cruise control system for an automotive vehicle, forcontrolling cruising of own vehicle with maintaining a distance to apreceding vehicle constant, comprising: traffic signal characteristicsobtaining means including image pick-up means having zooming means,image processing means obtaining a traffic signal characteristics byprocessing an image of said image pick-up means and communication means,for serving as measuring means for obtaining characteristics of atraffic signal ahead; road information obtaining means for obtainingintersection information including a distance to an intersection ahead;intersection arrival time calculating means for calculating arrivaltiming of the own vehicle and the preceding vehicle on the basis of adistance to the intersection, an own vehicle speed and a precedingvehicle traveling condition; traffic signal condition estimating meansfor estimating said condition of the traffic signal on the basis of thetraffic signal characteristics and said intersection arriving time;right and left turn control signal generating means for generatingoperation pattern of the own vehicle from a state of turn signal or aroute information to a destination generated by said road informationobtaining means to input to said control content modifying means;control content modifying means for modifying a content of cruisecontrol of the own vehicle depending upon said estimated traffic signalcondition; and alarm means for generating a corresponding alarmbeforehand of modifying the content of control.